Efficiency in pollen foraging by honey bees: Time, motion and pollen depletion on flowers of Sisyrinchium palmifolium Linnaeus (Asparagales: Iridaceae)

Abstract

Honey bees depend on flower resources (nectar and pollen) to supply individual and colony needs. Although behavioural studies already assessed optimum foraging patterns of bumblebees, honey bees foraging behavioural patterns have been poorly assessed. We used Sysirinchium palmifolium L. (Iridaceae), a low-growing, abundant and anthophilous grassland flower to test the hypotheses that Apis mellifera workers would i) spend more time, ii) visit a greater number of flowers, and iii) travel greater distances within patches of S. palmifolium which were newly opened or not been visited by other pollinators when compared to foraging on patches that were available to pollinators during its whole blooming period (only one day). In two different sunny days, we measured bee activities in an area opened for visitation during the whole anthesis (OP plot treatment) and another opened for visitation only half of anthesis (CL plot treatment). We observed bees spending more time, visiting more flowers and travelling more in S. palmifolium CL treatment than the OP plot treatment. Previous studies already showed bees alter their foraging behaviour in the lack of resources. Honey bees are able to remember the period of the day when resources are usually the higher, they probably detect the most promising period to gather resources on S. palmifolium flowers. Since A. mellifera is a pollinator with a wide-distribution and is considered an important cause of changes on native pollinator communities, we support additional studies evaluating its foraging behaviours to better understand how it explores flower resources.